<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>并集选择器</title>
  <style>
    /* div、p、span 文字颜色是红色 */
    div, p, span {
      color: red;
    }
  </style>
</head>
<body>
  <!-- 
    并集选择器: 选中多组标签设置相同的样式
      写法: 选择器1,选择器2,...,选择器3 {CSS属性}, 选择器之间用,隔开
   -->
   <div>div 标签</div>
   <p>p 标签</p>
   <span>span 标签</span>
</body>
</html>